1. Field of the Invention
The invention relates to image reading devices. In an image reading device, a carriage carrying an image sensor moves in a housing having a transparent panel, and an electric cable extending from the image sensor follows the movement of the carriage while maintaining a curved position.
2. Description of Related Art
A known image reading device, e.g., a flatbed scanner, a housing serves as a scanning table. In the housing, an image sensor such as a charge coupled device (“CCD”) or a contact image sensor (“CIS”), which is mounted on a carriage, scans a document in a specified direction so as to read an image of the document. A flatbed scanner may be used as a dedicated scanner or a scanning device incorporated in a copier or a multi-function device.
Electric signals output from the image sensor are transmitted to a control circuit board or the like through an electric cable, e.g., a strap-shaped type cable, which is called a flexible flat cable (“FFC”). An FFC may change shape and follow the movement of the carriage due to its flexibility. The FFC is routed such that the FFC is curved and reversed in the housing. For example, in a known image reading device, the FFC, which extends from an image sensor, is routed such that the FFC is curved from the upper surface toward the lower surface of a housing. With such a structure, a problem occurs in that the FFC, particularly the curved portion of the FFC, contacts the housing or a glass plate on which a document is placed.
In a known image recording device, e.g., a device described in one or more of Japanese Unexamined Patent Application Publications Nos. 2004-104392, 2005-57628, and 2008-17201, an FFC is placed in a recess or a groove in a lower surface structure of a housing, e.g., a scanner housing serving as a base member. With this structure, the FFC is prevented from contacting a glass plate or the housing, even when the housing has a low profile. In a known image recording device, e.g., the device described in Japanese Unexamined Patent Application Publication No. 2003-233138, an FFC is routed from a short side of an image sensor and along its long side. With this structure, an FFC is prevented from contacting a glass plate, e.g., the document table glass. In another known image recording device, e.g., the device described in Japanese Unexamined Patent Application Publication No. 11-64993, an end of an FFC is fixed to a housing obliquely downward. With this structure, the FFC is prevented from contacting a glass plate, e.g., the contact glass. The known image recording device also has a structure in which an end of the FFC is fixed such that the length direction of the FFC can be flexibly changed. With this structure, twisting of an FFC may be reduced.
In yet another known image recording device, e.g., the device described in Japanese Unexamined Patent Application Publication No. 2002-218161, an FFC is routed in a region corresponding to a region of a glass plate, e.g., document table glass, in which size markers are positioned. With this structure, even if the glass plate is smudged or scratched due to sliding contact by the FFC, the quality of a read image may not be adversely affected. In still another known image recording device, e.g., a device described in one or more of Japanese Unexamined Patent Application Publications Nos. 2004-104392, 2005-57628, and 2008-17201, a bottom of the recess or groove is positioned at a sufficient distance from the glass plate, such that the FFC does not contact the glass plate or the like. Thus, in the known image recording device, the lower surface of the housing protrudes by the length corresponding to the depth of the recess or groove, which makes it difficult to make the entire housing low-profile. In a multi-function device in which a device such as a printer is positioned below a scanner, components of the printer are to be arranged such that they do not interfere with the protrusion of the scanner, which may complicate design.
Moreover, in yet another known image recording device, e.g., the device described in Japanese Unexamined Patent Application Publication No. 2003-233138, a reaction force, which is generated by the curved portion of the FFC so as to allow the FFC to return to its original linear shape, is applied to an end of the image sensor in a direction in which the image sensor moves, e.g., a sub-scanning direction, whereby a position of the image sensor may be changed in a rotating manner. The reaction force fluctuates as the shape of the FFC changes while the FFC follows the image sensor. Therefore, during a scanning process with the image sensor, a relationship between the reading direction in a scanning direction, e.g., in the main scanning direction, and the sub-scanning direction changes, thereby deteriorating a quality of a read image.
In a known image recording apparatus, e.g., the image recording apparatus disclosed in Japanese Unexamined Patent Application Publication No. 11-64993, a space is required so as to allow the FFC to extend downward from its end fixed to the housing. That is, the structure requires an enough height inside the housing. With a low-profile housing having an inner space with a small height, however, it is difficult to provide the space for the FFC to extend downward from the end fixed to the housing.